ITS#4366 userPassword compare

I think this is in general a bad idea. It's already noted as such in the
README, which is fine. The code generally looks pretty good, although it would
need to be updated for cn=config support. Does anyone else see a reason to
integrate this and get it working with cn=config?
--
-- Howard Chu
Chief Architect, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/